Prasanth J created HIVE-5921: -------------------------------- Summary: Better heuristics for worst case statistics estimates for join, limit and filter operator Key: HIVE-5921 URL: https://issues.apache.org/jira/browse/HIVE-5921 Project: Hive Issue Type: Sub-task Affects Versions: 0.13.0 Reporter: Prasanth J Assignee: Prasanth J
This is a subtask of HIVE-5369. In worst case (i.e; absence of column statistics) HIVE-5849 improved the basic statistics with heuristics. But the heuristics failed to provide better estimates in few cases. For example: FILTER operator heuristics did not take into account the number of predicates and if the predicate contains partition column. Also, JOIN estimates were too aggressive and was not user configurable. -- This message was sent by Atlassian JIRA (v6.1#6144)